U.S. patent application number 11/871940 was filed with the patent office on 2008-12-25 for shape-changing tissue constrictor and methods of use.
This patent application is currently assigned to BOSTON SCIENTIFIC SCIMED, INC.. Invention is credited to Jeffrey V. Bean, Robert J. Rioux.
Application Number | 20080319435 11/871940 |
Document ID | / |
Family ID | 40137274 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080319435 |
Kind Code |
A1 |
Rioux; Robert J. ; et
al. |
December 25, 2008 |
SHAPE-CHANGING TISSUE CONSTRICTOR AND METHODS OF USE
Abstract
A tissue constrictor includes one or more shape-changing
materials that when activated aids in constricting a portion of an
organ or tissue in the body. In one embodiment, the constrictor
conducts electrosurgical or ablation energy to section tissue.
Inventors: |
Rioux; Robert J.; (Ashland,
MA) ; Bean; Jeffrey V.; (Fitchburg, MA) |
Correspondence
Address: |
CHRISTENSEN, O'CONNOR, JOHNSON, KINDNESS, PLLC
1420 FIFTH AVENUE, SUITE 2800
SEATTLE
WA
98101-2347
US
|
Assignee: |
BOSTON SCIENTIFIC SCIMED,
INC.
Maple Grove
MN
|
Family ID: |
40137274 |
Appl. No.: |
11/871940 |
Filed: |
October 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60851592 |
Oct 12, 2006 |
|
|
|
Current U.S.
Class: |
606/33 ; 606/139;
606/157 |
Current CPC
Class: |
A61B 18/1492 20130101;
A61F 5/005 20130101; A61B 2090/3954 20160201 |
Class at
Publication: |
606/33 ; 606/157;
606/139 |
International
Class: |
A61B 17/128 20060101
A61B017/128; A61B 17/125 20060101 A61B017/125; A61B 17/122 20060101
A61B017/122 |
Claims
1. A tissue constrictor, comprising: a band that includes at least
one shape-changing material therein that upon application of an
activation energy causes the band to assume a memory shape that at
least partially closes the band around a portion of a patient's
body.
2. The tissue constrictor of claim 1, wherein the band includes a
proximal end, a distal end, and a receiver that secures the
proximal end to the distal end.
3. The tissue constrictor of claim 1, wherein the band includes a
cover that is selectively inflatable to increase or decrease
pressure on the patient's body exerted by the constrictor.
4. The tissue constrictor of claim 1, wherein the band includes a
pair of legs that are joined at one end and are open at another end
and a shape-changing material having a memory shape that, when
activated, causes the pair of legs to compress together.
5. The tissue constrictor of claim 4, further comprising a ring
selectively positionable over the two legs to maintain the position
of the legs.
6. A gastric band for apportioning a stomach into an upper and a
lower region separated by a stoma having an open area between the
upper and lower stomach regions as a result of constricting the
stomach organ with the gastric band, the gastric band comprising: a
body including a proximal end and a distal end; wherein the body
includes at least one shape-changing material that assumes a memory
state such that the distal end of the body moves toward the
proximal end of the body when activated to apportion the stomach
into an upper and lower a region.
7. The gastric band of claim 6, wherein the at least one
shape-changing material is selected from the group consisting of a
shape-memory metal, a shape-memory metal alloy, and a shape-memory
plastic.
8. The gastric band of claim 6, wherein the body includes two or
more shape-changing materials, and wherein the two or more
shape-changing materials are selected from the group consisting of
a shape-memory metal, a shape-memory metal alloy, a shape-memory
plastic, and combinations thereof.
9. The gastric band of claim 8, wherein the two of more
shape-changing materials have different memory states and/or
different activation energies.
10. The gastric band of claim 6, wherein the body includes one or
more position stabilizers.
11. The gastric band of claim 10, wherein the one or more position
stabilizers include one or more spurs projecting outwardly from the
body for engaging tissue and/or one or more holes in the body for
receiving tissue therein.
12. The gastric band of claim 6, further comprising means for
anchoring the body in-situ.
13. The gastric band of claim 6, wherein the body includes an
imageable component that is visible with an external imaging
system.
14. The gastric band of claim 6, wherein the memory state of the
shape-changing material comprises either a partially closed shape
or a closed shape.
15. The gastric band of claim 6, further comprising a means for
adjusting the diameter of the closed band.
16. The gastric band of claim 6, wherein the body is
communicatively coupled to a source of activation energy.
17. The gastric band of claim 16, wherein the activation energy is
selected from a group consisting of electricity, heat, light,
radiation, and a chemical.
18. The gastric band of claim 6, further comprises a conductor
associated with the body, the conductor being coupled to a source
of radio frequency energy that allows the conductor to cut through
a patient's tissue
19. A method of applying a gastric band around the stomach of a
patient, comprising: creating a passageway around the stomach of a
patient; inserting a gastric band that includes a distal-end, a
proximal end, and a shape-changing material therein into the
passageway; activating the gastric band so that the gastric band
assumes a memory shape whereby the gastric band at least partially
closes around the stomach.
20. An assembly, comprising: a tissue constrictor; and a delivery
tool for delivering the tissue constrictor to a selected position
in-vivo; wherein either the tissue constrictor or the delivery tool
includes a shape changing component that aids in the positioning of
the tissue constrictor with respect to a selected body tissue or
organ when in-vivo.
21. The assembly of claim 20, wherein the delivery tool is selected
from a group consisting of a catheter, an endoscope, a trocar, a
dilator, an introducer, a needle with an axial bore, a hollow
tubing, a cannula, and a guide wire.
22. The assembly of claim 20, wherein the tissue constrictor is
removably coupled to the delivery tool.
23. The assembly of claim 20, wherein the tissue constrictor
includes a band having a proximal end and a distal end, and a
connector that couples the proximal end to the distal end.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/851,592, filed on Oct. 12, 2006, the disclosure
of which is expressly incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to medical devices in general and, in
particular, to devices for constricting tissue.
BACKGROUND
[0003] Obesity, especially morbid obesity, is associated with
substantial mental and physical health risks such as diabetes, high
blood pressure, and shortened life expectancy. Typical treatments
for obesity include dietary restrictions and increased exercise and
often have poor long-term success. Surgical options for the
treatment of obesity, frequently restricted to morbid obesity, may
include gastric bypass surgery, small bowel bypass surgery, and
reduction of stomach volume by surgery (e.g., stomach stapling).
While effective for some patients, these procedures may have
unsatisfactory long-term results and may also cause other negative
health effects. Less traumatic techniques for reducing available
stomach volume have included balloons placed in the stomach.
[0004] Another method for treating obesity is to place a
constrictive band around the exterior of the stomach to effectively
separate the stomach into a small upper region near the esophagus
and a larger lower region of the stomach beyond the constriction.
These two portions are separated by a stoma, i.e., a small opening
and surrounding tissue that is created by the constrictive band.
Gastric bands retard movement of food from the upper stomach region
to the lower stomach region as a result of the food having to pass
through the restriction of the newly created stoma. With the
gastric band in place, the patient should feel sated with less food
as a result.
[0005] Adjustable gastric bands have been developed allowing
post-operative resizing of the open area of the stoma with
minimally invasive procedures. Adjustment may be accomplished using
an inflatable reservoir for a gas or, more typically, a saline
solution. Frequently, an access port is placed just under the skin
during the gastric banding procedure. The access port is connected
to the adjustable gastric band by tubing, thereby allowing
inflation of an inflatable reservoir in the band by an introduction
of gas or fluid with a syringe and needle inserted through the skin
and into the access port. As the reservoir fills, it expands and
compresses the stoma tissue inwardly, thereby reducing the open
area of the stoma. The reservoir may also be drained or vented to
increase the open area of the stoma.
[0006] Modern laparoscopic procedures are typically used to place
gastric bands either with or without a calibration device into the
stomach through the esophagus for determining the inner diameter
and placement of the gastric band being implanted. Placement of a
gastric band usually requires sectioning of tissue in the
retrogastric space to provide room for the band to encircle the
fundus, i.e., a "retrogastric tunnel." Many moderm gastric band
procedures employ the Kuzmak technique, wherein the retrogastric
tunnel passes posterior to the stomach from the lesser curvature of
the stomach, about 1 cm below the gastroesophageal junction, to the
angle of His on the greater curvature of the stomach. For devices
with an access port tethered to the gastric band by tubing, the
port is typically also inserted during the same procedure.
[0007] Laparoscopic procedures can require the placement of five to
seven cannulae, typically six cannulae, into the abdomen of the
patient, each cannula opening typically being between 5 mm and 30
mm in diameter. Therefore, the placement of a gastric band can be a
fairly invasive procedure that requires a substantial recovery
time. Given these problems, there is a need for a mechanism that
simplifies the placement of a tissue constrictor in a patient.
SUMMARY
[0008] To address the above-mentioned concerns, several embodiments
of the present invention are directed to tissue constrictors that
include a shape-changing component(s) or material(s). In some
embodiments, the constrictor is used as a gastric band that curves
around the stomach to facilitate its deployment. In another
embodiments, the tissue constrictor may include one or more
position stabilizers, for example, spurs or suture points for
securing the band. Additional embodiments of the present invention
are adapted to section tissue, such as by delivery of
high-frequency electrosurgical energy through the band. Further
embodiments of the present invention are directed to delivery tools
having a shape-changing component(s) or material(s). The delivery
tools are used to properly place a tissue constrictor in-vivo.
[0009] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This summary is not intended to identify
key features of the claimed subject matter, nor is it intended to
be used as an aid in determining the scope of the claimed subject
matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The foregoing aspects and many of the attendant advantages
of this invention will become more readily appreciated by reference
to the following detailed description, when taken in conjunction
with the accompanying drawings, wherein:
[0011] FIG. 1A illustrates a typical number and placement of entry
points into the abdominal cavity of a patient undergoing bariatric
surgery for placement of a gastric band device;
[0012] FIG. 1B illustrates a conventional placement of a
retrogastric tunnel for placement of a gastric band around the
stomach of a patient;
[0013] FIG. 1C illustrates a conventional tool placed in a
retrogastric tunnel for aiding in the placement of a gastric
band;
[0014] FIG. 1D illustrates a conventional hydraulically or
pneumatically adjustable gastric band separating a stomach into an
upper and lower region by creating a stoma between the upper and
lower stomach regions;
[0015] FIG. 1E illustrates a conventional placement location for an
access port used to adjust the volume or pressure in a
hydraulically or pneumatically adjusted gastric band;
[0016] FIGS. 2A-2D illustrate one embodiment of a tissue
constrictor in accordance with the present invention;
[0017] FIGS. 3A-3B illustrate another embodiment of a tissue
constrictor in accordance with the present invention;
[0018] FIGS. 4A-4B illustrate another embodiment of a tissue
constrictor in accordance with the present invention;
[0019] FIGS. 5A-5B illustrate another embodiment of a tissue
constrictor in accordance with the present invention;
[0020] FIGS. 6A-6C illustrate another embodiment of a tissue
constrictor in accordance with the present invention;
[0021] FIG. 7 illustrates one or more position stabilizers included
in a tissue constrictor in accordance with another embodiment of
the invention; and
[0022] FIG. 8 illustrates a system for supplying activation energy
to a tissue constrictor in accordance with one embodiment of the
present invention.
DETAILED DESCRIPTION
[0023] Embodiments of the present invention will now be described
with reference to the accompanying drawings where like numerals
correspond to like elements. Embodiments of the present invention
are generally directed to tissue constrictors for use in
compressing a patient's tissue or organs. The following description
depicts the primary use of the tissue constrictors as a gastric
band. However, other suitable uses for constricting other tissues,
vessels, or organs in the body are contemplated to be within the
scope of the present invention, as claimed.
[0024] Bariatric surgery for placement of a gastric band typically
includes the placement of six entry points into the abdomen of a
patient, as shown in FIG. 1A. These six entry points 100 are
usually formed with trochars and cannulae that are between 5 mm and
30 mm in diameter to permit, among other actions, insufflation,
observation, retraction, and manipulation of tissue, sectioning of
tissue, placement of a gastric band, and providing an optional
access port. Once the abdominal cavity is accessed, a retrogastric
tunnel may be formed in the connective tissue around the outer
surface of the stomach to accommodate the gastric band.
[0025] The creation of the retrogastric tunnel may be performed by
a technique that includes the creation of two tunnels. As shown in
FIG. 1B, one tunnel 110 extends from the lesser curvature of the
stomach and one tunnel 120 extends from the greater curvature of
the stomach. The tunnels join posterior to, and slightly below, the
point of the gastroesophageal junction 130 and the stomach 140.
[0026] Once the first and second tunnels are created and joined
together around the stomach, an instrument 152 is inserted through
the connected retrogastric tunnel 150 to pull a gastric band
through the tunnel posterior to the stomach organ 140, as shown in
FIG. 1C. A gastric band 160 may then be inserted through the tunnel
150 and closed around the stomach organ 140, separating the stomach
140 into an upper region 170 and a lower region 180, as shown in
FIG. 1D. Constriction of the gastric band 160 creates a stoma
between the two regions 170 and 180. Where the gastric band 160 is
adjustable and includes an access port 190, the port is typically
attached to the adjustable gastric band 160 by tubing. As shown in
FIG. 1E, the access port 190 is often placed just under the skin
near the front, left, lower rib cage to allow easy access and
palpation for adjustment of the gastric band by injection of a
fluid or gas.
[0027] As will be appreciated, the conventional technique for
placing a gastric band in a patient is relatively invasive. Some
embodiments hereinafter described aid the deployment of a gastric
band around the stomach during bariatric surgery, potentially
simplifying the surgery.
[0028] As will be described in further detail below, some
embodiments of the tissue constrictor are suitable for use as a
gastric band that incorporates a shape-changing material. The
shape-changing material facilitates deployment of the band during
bariatric surgery. Shape-changing materials include but are not
limited to materials that have a "memory" shape. Some
shape-changing materials can be deformed and will return to, or
near to, the "memory" shape upon application of a trigger signal,
such as an activating energy (electricity, heat, light, chemical,
etc). Shape-changing materials include, but are not limited to,
shape-changing metals or metal alloys and shape-changing plastics.
One example of a suitable shape-changing metal is Nitinol.TM..
Other suitable shape-changing materials include, but are not
limited to, thermoplastics such as shape memory polyurethanes,
cross-linked trans-polyoctylene rubber, polynorbornene polymers and
copolymers and blends thereof with styrene elastomer copolymers,
such as Kraton, and polyethylene; styrene butadiene copolymers;
PMMA; polyurethane; cross-linked polyethylene; cross-linked
polyisoprene; polycycloocetene; bioabsorbable shape memory polymers
such as polycaprolactone, copolymers of (oligo)caprolactone, PLLA,
PL/DL A copolymers, and/or PLLA PGA copolymers; and Azo-dyes and/or
Zwitterionic and/or other photochromatic materials such as those
described in "Shape Memory Materials" by Otsuka and Wayman,
Cambridge University Press (1998), the entire contents of which are
being incorporated herein by reference.
[0029] FIGS. 2A-2D illustrate one embodiment of a tissue
constrictor formed in accordance with aspects of the present
invention. The tissue constrictor, such as a gastric band 200, is
positioned at a desired location in the body via a delivery
catheter 250. The delivery catheter 250 may be routed through an
additional catheter, endoscope, a trocar, a dilator, an introducer,
a needle with an axial bore, a hollow tubing, a cannula, or the
like. Some bariatric procedures may obviate the need for the
additional introducer, for example, during open bariatric surgery,
as opposed to laparoscopic or endoscopic procedures, whereby the
abdomen is directly accessed through one or more incisions.
Therefore, where an access device is inappropriate or unnecessary,
the gastric band 200 may be employed without an additional access
device.
[0030] In the embodiment shown, the gastric band 200 includes a
distal tip 210, a central band portion 220 extending proximally
from the distal tip, and a proximal end 230. A receiver 240
positioned at the proximal end 230 of the band 220 has a tip mating
mechanism that engages and secures the tip 210 to hold the band 200
around a desired object such as a portion of the stomach. In one
embodiment, the proximal end 230 of the gastric band 200 is
removably attached to the distal end of a delivery tool 260 that is
routed in the delivery catheter 250 as shown in FIG. 2B. The
gastric band 200 may be inserted into the abdominal cavity of a
patient through an access device while attached to the distal end
of the delivery tool 260. Once in place, the gastric band 200 is
activated to bend the gastric band at least partially around the
stomach, as will be described in further detail below.
[0031] The gastric band 200 may be comprised of a single type of
shape-changing material such as Nitinol.TM.. Alternatively, the
gastric band 200 may comprise a plurality of materials, for
example, as laminated layers of structurally different
shape-changing materials, or the same shape-changing material
having different memory shapes. Alternatively, one or more
shape-changing materials may be combined with non-shape-changing
materials.
[0032] In one embodiment, the materials used to construct the
gastric band 200 are selected so that, upon activation, the gastric
band will change to its memory shape when placed in the body (e.g.,
temperature activated).
[0033] FIGS. 2C and 2D illustrate one possible "memory" state shape
of the gastric band 200. After the shape-changing material of the
gastric band is actuated, the gastric band 200 transitions to the
memory state shape. For example, if the memory state shape is as
depicted in FIG. 2C, the gastric band 200 attempts to return to a
generally closed shape by bending into a circular configuration
such that the distal tip 210 is in contact with the receiver 240
(or nearly so) at the proximal end 230 of the band. In the
embodiment shown, the distal tip 210 of the band 200 includes a key
212 having one or more holes 214 therein. The key 212 at the distal
tip is sized to fit within a slot 242 in the receiver 240. The
receiver 240 includes a locking mechanism such as one or more pins
that engage the holes 214 to secure the tip 210 in the receiver
240. The tip may be fixedly secured or releasably secured in the
receiver 240. For example, the pins may be spring biased in order
to allow them to be removed from the holes 214 so that the tip 210
can be withdrawn from the receiver 240.
[0034] In some embodiments, a spring force is associated with the
materials used to form a gastric band 200. As a gastric band 200
attempts to return to its "memory" state shape upon actuation, this
spring force may be exerted on tissue structures that are
positioned within the closing band structure. If the spring forces
are not sufficient to overcome the resistance imposed by these
interfering structures, the gastric band 200 may be prevented from
attaining the final "memory" state shape. Therefore, in one
embodiment, the gastric band 200 is designed with the correct
geometry, materials, and size to accomplish a complete or nearly
complete closure in order to create a desired constriction of
tissue or organ around which it is placed. Where the spring force
is insufficient to close the gastric band, the final closure of the
band may be accomplished manually, such as with another tool or by
hand.
[0035] As indicated above, once the gastric band 200 is closed, the
distal tip 210 may or may not be removed from the receiver 240 at
the proximal end 230 of the band. The design of the gastric band
200 may be intended for extended or permanent implantation into a
patient and, thus, the distal tip 210 may be non-removably engaged
with the receiver 240. Alternately, the connection between the
distal tip 210 and the receiver 240 may be removable to facilitate
later removal of the device from the patient.
[0036] Examples of non-removable connections between the tip
portion 210 and the receiver 240 include sutures, welds, crimps,
thermal glues, chemical glues or other adhesives, mechanical
friction locks, hooked structures (either a hook structure in the
receiver 240 that engages the distal tip 210 or a hook in distal
tip 210 that engages a cooperating structure in the receiver 240),
cross-pin structures, mechanical locking structures (for example
zip-tie closures, key-type locks, cam locks, flexible tangs and
male and female fasteners and components, cooperating slots, etc.),
strong permanent or electromagnetic components, screws or bolts
either perpendicular to or parallel with the distal tip 210, or
rivets, among others.
[0037] Further examples of removable connections between the distal
tip portion 210 and the tip mating mechanism 240 include any
breakable, reversible, or actuatable connections listed above.
Additionally, removable connections may, for example, include hook
and loop-type materials such as Velcro.TM. or dissolvable sutures,
among others, and may also include electrolytic joints, adhesives,
etc.
[0038] In some embodiments, the proximal end 230, distal tip 210,
and/or receiver 240 may be used to adjust the inner diameter of the
closed gastric band 200. In one embodiment, the diameter of the
gastric band is adjusted by moving the tip portion out of the
receiver. This may be accomplished by passing the tip portion 210
through the receiver 240 in a manner similar to a zip-tie.
Alternatively, this may be accomplished by moving the position of
the receiver 240 along the band 200.
[0039] In yet another embodiment, the diameter of the gastric band
can be changed by compressing or expanding the band 200 while the
distal tip 210 is in the receiver 240. Changing the diameter of the
gastric band 200 may be accomplished by the use of ancillary
structures such as reversibly inflatable reservoirs or mechanical
actuators placed between the band and the surrounding tissue.
[0040] A removable delivery tool 260 may be associated with the
gastric band 200. The delivery tool 260 may be a general purpose
laparoscopic or endoscopic tool well known in the art, or may be a
tool specifically associated with particular embodiments of the
gastric band 200. Generally, the delivery tool 260 is an elongated
rod or shaft that may be used to place, manipulate, deploy,
activate, or adjust, or some combination thereof, a gastric band
200 during installation, removal, or adjustment. In one embodiment,
the delivery tool 260 comprises a rigid shaft or thin bar having
the gastric band 200 secured at one end thereof and a length
selected so that a user can move the gastric band from the proximal
end of the delivery catheter 250. Alternate embodiments of the
delivery tool 260 may comprise a flexible shaft, wherein the
flexible shaft still permits guidance of the gastric band 200 to a
desired location. Flexible shaft embodiments generally are also
torsionally stiff to permit rotation of the gastric band 200 from
the proximal end of the tool. In addition, the shaft may have
variable stiffness or a controllable stiffness, steerability,
etc.
[0041] In one embodiment, the delivery tool 260 is communicatively
connected, in addition to being removably connected, to a gastric
band 200. For example, the delivery tool 260 may include one or
more electrical conductors to transmit electrosurgical energy to
the gastric band 200. In an alternative embodiment, the delivery
tool 260 comprises at least one fluid or gas conduction lumen to
transmit said fluid or gas to, or near to, the gastric band 200.
The transmitted fluid or gas may, for example, be used to heat or
cool the gastric band 200, to inflate or deflate a reservoir, or to
clean the gastric band 200, or some combination thereof, among
other actions. Multiple features may be embodied in shaft and band.
For example, the delivery tool 260 may include a fluid conduit and
a conductor for activating the band material and/or the fluid
contained therein.
[0042] In one embodiment, the delivery tool 260 includes one or
more electrical conductors to transmit sufficient electrical energy
to an electroresistive heating element that is thermally coupled to
the gastric band in order to raise the temperature of the gastric
band 200 or a component thereof to a temperature sufficient to
activate the shape-changing material. A still further embodiment of
a delivery tool 260 includes one or more thermally conductive
elements such as copper rods or other heat conducting metals,
capable of transmitting externally generated thermal energy to
raise the temperature of a shape-changing material in the gastric
band 200 to a level sufficient to activate the shape-changing
material into its memory state. If the gastric band is made of an
electrically conductive material, the actuation energy may be
delivered directly to the band. If not conductive, the actuation
energy may be coupled to a wire or printed circuit trace on the
band that causes the band to assume its memory shape. In other
embodiments, the shape-changing material may be activated by light
and the actuation energy delivered from a light source by an
optical fiber or light source positioned near the band.
[0043] The delivery tool 260 may be removably connected to the
gastric band 200 by means of a severable link, including, for
example, a thinned portion, a narrow portion, a necked portion, a
perforated portion, and/or electrolytic or melting links, among
others. Alternatively, the delivery tool 260 shaft may be separated
from the gastric band 200 by bending, rotating, or pulling with
sufficient force, or applying an energizing force, among others.
The removable connection may also comprise mechanical removable
connections, for example, mechanical severing devices, friction
connections such as a pin and socket, screw threads, or actuatable
mechanisms such as retractable hooks, among others. Additional
embodiments of the removable connection may comprise
permanent-magnetic or electromagnetic removable connections.
Further additional embodiments of the removable connection may
include a breakable adhesive connection such as a chemically or
thermally weakened or destroyed adhesive connection, among
others.
[0044] Once in the desired location, the gastric band 200 is
separated from the delivery tool 260, as shown in FIG. 2D.
[0045] FIGS. 3A-3B depict an alternative embodiment of the present
invention. In this embodiment, a tissue constrictor that may be
used as a gastric band 300 has a generally "horseshoe" shape
including a pair of semicircular legs 302, 304 that are joined at
one end and are spaced apart by a gap 306 at their tips. A leg
retaining mechanism 310 is selectively positionable over the area
where the legs 302 and 304 are joined together. By moving the leg
retaining mechanism 310 proximally or distally, the legs are
squeezed together or are allowed to expand apart. In one
embodiment, the legs 302, 304 of the gastric band are made of a
shape-changing material such as Nitinol.TM.. The distal tips of the
legs 302, 304 can remain apart or may be joined together upon
activation of the shape-changing material by an activation energy.
Such energy may include resistive heating of the legs.
Alternatively, externally generated activation energy can be
delivered to the gastric band 300 through an appropriate
conduit.
[0046] The gastric band 300 is connected to a delivery mechanism by
a breakable link 322. In one embodiment, the breakable link
includes one or more pins that are affixed in corresponding holes
on the portion of the band where the legs 302 and 304 are joined.
The pins are secured to the band with a friction fit or are
breakable so that the application of a sufficient force will break
the connection. In the embodiment shown, the delivery mechanism
includes a nested pair of catheters 320 and 340. The outer catheter
340 applies distal pressure to the leg retaining mechanism 310,
while the gastric band 300 is pulled proximally by the catheter 320
in order to advance the leg retaining mechanism 310 distally over
the legs 302, 304, thereby compressing or holding them together.
FIG. 3B illustrates the gastric band 300 freed from the delivery
mechanism.
[0047] In one embodiment, the distal tips of the legs 302, 304
close around a tissue, vessel, or organ by the application of an
activation energy to the shape-changing material. The tips of the
legs may become engaged via a mechanical, magnetic, or an adhesive
closure mechanism, or the like, in order to create a
circumferential band around the tissue. In addition, the leg
retaining mechanism 310 engages the outer surface of the legs 302,
304 with a friction enhancing mechanism to prevent the retaining
ring from inadvertently sliding with respect to the legs so that
the band remains closed with the desired tension.
[0048] FIGS. 4A and 4B show yet another alternative embodiment of
the present invention. In this embodiment, a tissue constrictor
that may be used as a gastric band 400 has a distal tip 402 that is
securable in a receiver mechanism 404 at the proximal end of the
band. In the embodiment shown, the cross section of the gastric
band between the distal tip section 402 and receiver mechanism 404
is generally curved on its inner surface so that the band smoothly
engages tissue with no sharp edges and further adds pressure around
the tissue when the band is closed. The curved cross section may be
provided by forming the gastric band of a shape-changing plastic
material, as described above. Alternatively, a shape-changing metal
can be used and covered with a plastic or rubberized biocompatible
material to provide the desired shape. The gastric band 400 is
releasably secured to a delivery mechanism 440 that serves to place
the gastric band in the patient. In addition, the delivery
mechanism 440 may deliver a trigger signal, such as an activation
energy, to the band in order to cause the shape-changing material
to return to its memory state.
[0049] In the embodiment shown in FIGS. 4A and 4B, the receiver
mechanism 404 at the proximal end of the gastric band 400 includes
a window having a number of flaps 412 therein. A hole in the center
of the window receives a button 414 at the distal end of the band.
The button includes a groove 416 about its circumference. Upon
entry of the button 414 into the window 410, the edges of one or
more of the flaps 412 seat within the groove 416 to secure the
distal end of the band to the proximal end as shown in FIG. 4B.
[0050] The gastric band 400 is releasably secured to a delivery
mechanism 440 so that upon delivery of sufficient force or an
activation energy, the gastric band 400 is released.
[0051] FIGS. 5A and 5B illustrate yet another embodiment of a
tissue constrictor in accordance with the present invention. In
this embodiment, the tissue constrictor formed as a gastric band
450 has a generally circular cross-sectional shape. A C-shaped
connector 460 at the distal end of the band includes a pair of jaws
that engage a corresponding post 470 positioned at the proximal end
of the band. Alternatively, the C-shaped connector could be placed
at the proximal end of the band and a corresponding bar or post
positioned at the distal end of the band. During use, activation of
a shape memory material that forms the band 450 or is included
within the gastric band 450 causes the band to close completely or
partially upon itself such that the distal end of the band can be
secured to the proximal end of the band. In one embodiment of the
invention, the gastric band 450 is coated with a polymeric or other
biocompatible material such that the outer shape of the band is
generally round. In an alternative embodiment of the invention, the
gastric band 450 may include an outer cover that is inflatable with
a gas or a liquid. Inflation of the outer cover further increases
the pressure exerted by the band when it is closed. The outer cover
may be further inflated or deflated to increase or decrease
pressure as desired. The gastric band 450 is connected to a
delivery mechanism 480 via a breakable link. As shown in FIG. 5B,
the delivery mechanism 480 includes a post 482 that is received in
a corresponding hole 456 at the proximal end of the band. Upon
application of sufficient force or an activation energy, the post
482 is released from the hole 456, thereby releasing the band 450
from the delivery mechanism 480.
[0052] In one embodiment of the invention, the hole 456 may further
be coupled to a source of air or liquid via a tube (not shown) and
a reservoir secured under the patient's skin or at a similar
location that allows the gastric band to be inflated or deflated as
desired.
[0053] FIGS. 6A and 6B illustrate yet another alternative
embodiment of a tissue constrictor in accordance with the present
invention. In this embodiment, the tissue constrictor is used as a
gastric band 500 having a distal tip 510 and a proximal end 520. In
this embodiment, the proximal and distal ends form a cooperating
tab and slot to secure the distal end to the proximal end. In the
embodiment shown, the proximal end includes a loop 522 under which
a tab at the distal end 510 is fitted. A pin or extension in the
loop 522 fits within a slot 512 in the proximal end of the band to
secure the proximal tab within the loop 522. In the embodiment
shown, the proximal end 520 of the band is folded against the inner
circumference of the band at a hinge 524. As shown in FIG. 6C, upon
application of an activation energy, the band 500 assumes its
memory state whereby the proximal end 520 is moved away from the
inner circumference of the band and the distal tip 510 is moved
toward the proximal end of the band. The distal tip 510 can then be
fitted within the loop 522 such that the proximal end is secured to
the distal tip. The gastric band 500 is delivered to a desired
location with a delivery mechanism 540. Upon application of
sufficient force or activation energy, a link between the delivery
mechanism 540 and the gastric band 500 is broken, thereby leaving
the gastric band 500 at a desired location in the patient's
body.
[0054] In some embodiments of the invention, the strip that forms
the band may include one or more rib structures along the band
portion. The use of one or more rib shapes may provide additional
rigidity and reduce or prevent twisting or rolling of the tissue
constrictor after implantation in the patient. The rib shapes may
be concave, convex, solid, or hollow features. The one or more rib
structures may or may not be present prior to activation of a
memory material comprising the gastric band. The rib structures
themselves may or may not be formed out of a shape-changing
material and may or may not have the same activation energy source
and level as any other shape-changing material comprising the strip
of the gastric band. The geometry of the rib structures may vary in
number, orientation, width, length, depth, and height either as a
group, including a group of one rib, or as individual ribs, where
more than one rib is used.
[0055] In another embodiment of the invention, the tissue
constrictor may include one or more shape-changing stabilizers. The
stabilizers are intended to reduce or prevent movement or twisting
of a gastric band. As shown in FIG. 7, a gastric band 600 includes
one or more position stabilizers that include spurs 602, anchors,
or the like, that aid in fixing the position of the band with
respect to the stomach or other location in the body. For example,
the gastric band may include one or more holes 604 into which
tissue can extend to secure the position of the band. Position
stabilizers may or may not be formed of the same shape-changing
material or materials as the gastric band itself. The position
stabilizers may or may not include other materials in addition to a
shape-changing material. In one possible embodiment, a spur-type
relative position stabilizer includes a spur 602 that, upon
activation, extends out of the plane of the band 600 to engage
adjacent tissue in order to anchor the band. The particular angle
and orientation of the spur "memory" shape state may be selected
based on the intended use of the tissue constrictor.
[0056] In other embodiments, anchoring is achieved by surface
structure such as a roughened surface, bumps, pits, spikes,
filaments, patterns, etc. In other embodiments, the device promotes
tissue growth, where permanency is desired. In another embodiment,
the shape-changing component is an introduction catheter, a guide
wire, or other ancillary component that bends itself around a
desired structure, such as a retrogastric tunnel. The guidewire can
then lead the constriction device around the tunnel for proper
placement, or the constriction device can be situated on the
shape-changing delivery device as it is delivered. The delivery
device may create the tunnel with energy.
[0057] In some embodiments of the invention, the shape-changing
materials used to form the tissue constrictor can be tailored such
that the application of radio frequency energy both causes the
gastric band to act as a tissue cutting device, as well as causes
the gastric band to assume its memory shape, thereby surrounding
the desired portion of the stomach. When used as a gastric band,
the application of the radio frequency energy causes the band to
tunnel around the esophageal neck above the stomach. Because the
esophagus has a predictable diameter, the delivered band can be
selected to have the proper predetermined diameter when closed.
[0058] FIG. 8 illustrates one embodiment of a system for supplying
the radio frequency energy to a tissue constrictor 700 that is
delivered to desired location by a delivery catheter 702. A radio
frequency generator 704 is in electrical contact with the tissue
constrictor 700. A conductor on the tissue constrictor or the
tissue constrictor itself acts as a radio frequency knife, cutting
tissue surrounding the constrictor. Current is returned to the
radio frequency generator 704 from an external patient pad 706.
Alternatively, a return electrode may be placed in the catheter
702. The radio frequency energy delivered cuts the tissue and may
activate the shape-changing material to assume its memory state. In
some embodiments, the radio frequency generator may supply only an
activation energy to activate the shape-changing material.
[0059] A tissue constrictor of the present invention may also
include an imageable component, such as a radiopaque marker.
Incorporation of an imageable component into the band may aid in
placement, monitoring, or removal of such a constrictor. As an
example, an embodiment with a Nitinol.TM. band portion is easily
viewable with x-ray imaging devices because Nitinol.TM. is
radiopaque. The imageable component may or may not be a
shape-changing material, and may or may not serve any other purpose
than to allow imaging of the imageable component itself. Other
embodiments of the tissue constrictor includes an imageable
component that is easily viewable via magnetic resonance imaging
(MRI) techniques.
[0060] While the preferred embodiments of the invention have been
illustrated and described, it will be appreciated that various
changes can be made therein without departing from the scope of the
invention. For example, although the disclosed embodiments of the
invention are directed to gastric bands, the present invention
could be used to constrict blood vessels, muscles, bones, internal
organs, or the like. In addition, various band widths may be used
to cover more surface area. More than one band could be displayed
or the bands can be made easily removable.
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